1. Mr.Kinton Honors Chemistry Enloe High School
Chemical Reactions
Mr.Kinton
Honors Chemistry
Enloe High School

2. Introduction to Chemical Reactions
Law of Conservation of mass: total mass of all substances before and after a chemical reaction remains constant
In chemical reactions, the atoms involved are combined, separated, or rearranged
During these processes atoms are not subdivided, created, or destroyed

3. Chemical Reactions/Equations Vocabulary
Chemical equation: a representation of a chemical reaction using the formulas of the reactants and products
H2 (g) + O2 (g) H2O (l)
+: interpreted as reacts with
: interpreted as produces
Reactant: starting substance in a chemical reaction and appears to the left of the arrow in a chemical equation
Product: substance that is produced in a chemical reaction and appears to the right of the arrow in a chemical equation

4. Writing a Chemical Equation
Methane reacts with oxygen to produce carbon dioxide and water
Sodium and chlorine react to form sodium chloride
Hydrochloric acid and potassium hydroxide yields potassium chloride and water

5. Chemical Reactions/Equations Vocabulary
Balanced: used to describe an equation when the total number of atoms on each side are equal
Coefficients: numbers that are placed in front chemical formulas in order to balance an equation
Skeleton equation: another term used to describe an unbalanced chemical equation

6. Chemical Equations Skeleton Equation Balanced Equation
H2 (g) + O2 (g) H2O (g)
2H2 (g) + O2 (g) H2O (g)

7. How to Balance a Chemical Equation
Write the skeleton equation showing the correct formulas for the reactants and the products
Determine the number of atoms of each type on each side of the equation
Use coefficients to balance the equation
Subscripts should never be changed because that changes the identity of your substance
Reduce the coefficients to the lowest whole number possible

8. Balancing Equations CH4 + O2 CO2 + H2O Na + Cl2 NaCl
HCl + KOH KCl + H2O

9. Physical States and Chemical Reactions
We can also include the physical state of our element or compound in our equation
Liquids (l): only 2 elements are liquids at room temperature; Hg and Br
Gases (g): H, N, O, F, Cl, He, Ne, Ar, Kr, Xe, and Rn are the only elements that exist in the gas phase at room temperature
Solids (s): Every other element is a solid at room temperature

10. Physical States and Chemical Reactions
Ionic Compounds exist as solids at room temperature
Covalent compounds with a molecular weight less than 100 amu will be gases
Aqueous (aq): substance that has been dissolved in water (ionic compounds, acids, bases)
As we encounter other compounds of interest we will discuss their physical states

11. Other Information Given in Chemical Equations
Additionally, reactions that require energy, light, or electricity can also be indicated in a chemical equation
Heat: Δ
Electricity:
Light: hν
These things can be found above the arrow

12. Indicators of a Chemical Reaction
During a chemical reactions a chemical change is taking place
That means that the process is not easily reversible
When a chemical reaction occurs one or more of the following could be observed
Formation of a gas
Formation of a precipitate
Liberation of heat or light
Color change

13. How to Identify a Gas
In the chemical reactions we will examine the most common gases produced are H2, O2, and CO2
The following tests can be used to identify the following gases:
H2- take a burning splint and listen for a “pop”
O2- take a glowing splint and observe it get brighter
CO2- take a burning splint and observe the flame be extinguished

14. Types of Chemical Reactions
For our class all chemical reactions will fall into one of 5 categories:
Synthesis or Combination
Decomposition
Combustion
Single-replacement/displacement
Double-replacement/displacement
Acid-base neutralization

15. Synthesis/Combination Reactions
Chemical reaction where 2 or more reactants combine to form 1 product
General equation: A + B AB
Examples
C + O CO2
N2 + H2 NH3
CaO + H2O Ca(OH)2

16. Synthesis/Combination Reactions
There are 3 different types of synthesis reactions:
Formation of a binary compound: same as the general equation
Metal oxide and water: MO + H2O Base
Nonmetal oxide and water: (NM)O + H2O Acid

17. Synthesis/Combination Reactions
Identify the type of synthesis reaction, predict the products, give physical states, and balance the equation
Lithium and oxygen reacting
The formation of H2SO4
Aluminum oxide and water reacting

18. Decomposition Reactions
Chemical reaction where 1 reactant will break apart into 2 or more products
General Equation: AB A + B
Examples:
KClO3 KCl + O2
PbCO3 PbO + CO2
Cu(OH)2 CuO + H2O

19. Decomposition Reactions
There are 6 different types of decomposition reactions:
Binary compounds: same as general equation
Metallic carbonates: MCO3 MO + CO2
Metallic bicarbonates: MHCO3 MCO3 + CO2 + H2O
Metallic hydroxides: MOH MO + H2O
Metallic chlorates: MClO3 MCl + O2
Oxyacids: Oxyacid (NM)O + H2O

20. Decomposition Reactions
Identify the type of decomposition, predict the products, give physical states, and balance the equation:
Decomposition of sodium oxide
Decomposition of aluminum chlorate
Decomposition of potassium bicarbonate

21. Single Replacement/Displacement Reactions
Type of chemical reaction where a more reactive element will replace a component in a compound to form new products
General Equation: A + BC AC + B
Examples
Li + NaCl LiCl + Na
F2 + NaCl NaF + Cl2
Zn + HCl ZnCl + H2
Elements will be in their physical state at room temperature and compounds will be in aqueous solutions

22. Single Replacement/Displacement Reactions and the Activity Series
A list of metals in order of decreasing ease of oxidation (losing electrons)
In order for an element to replace another it must be higher on the activity series than the element it is trying to replace
Metals can only replace other metals and nonmetals can only replace nonmetals
In some cases no reaction will occur

23. Activity Series
Determine whether or not the following element can replace the other:
K replacing H
Mn replacing Ca
Cu replacing Au
I replacing Cl

24. Single Replacement/Displacement Reactions
There are 4 different types of single replacement reactions:
Metal-metal replacement: same as general
Active metal replaces H from water: M + H2O MOH + H2
Active metal replaces H from acid: M + HX MX + H2
Halide-halide replacement: D + BC BD + C
Remember, metals replace metals, and nonmetals replace nonmetals

25. Single Replacement Reactions
Identify the type of single replacement reaction, predict the products, predict physical states, and balance the equation:
Magnesium and calcium phosphate
Aluminum and hydrochloric acid
Bromine and calcium iodide

26. Double Replacement/Displacement Reactions
Chemical reaction that takes place in aqueous solution where ions switch partners and either a precipitate or a non electrolyte is formed
Precipitate: solid that is produced when 2 aqueous reactants combine to form new products
General Equation: AB + CD AD + CB
Examples:
Pb(NO3)2 (aq) + 2KI(aq) 2KNO3 (aq) + PbI2 (s)
HCl (aq) + NaOH (aq) NaCl (aq) + H2O (l)

27. Double Replacement/Displacement Reactions and Solubility Rules
Not all substances are soluble in water
When all of your reactants and products are aqueous, no reaction takes place
Use these rules to help determine the physical states of double replacement reactions only

28. Solubility
Determine whether the following compounds would be soluble in water:
NH4NO3
CaF2
Li2SO4
CaCO3
Sr(OH)2

29. Double Replacement Reactions
There are 2 different types of double replacement reactions:
Formation of a precipitate: same as general
Acid-Base neutralization: HX + MOH MX + H2O
Acids will always be aqueous
Check the solubility rules to determine if the base is soluble
Water is always a liquid

30. Double Replacement Reactions
Identify the type of double replacement reaction, predict the products, include physical states, and balance the equation:
Sodium phosphate and zinc sulfate
Sulfuric acid and potassium hydroxide
Ammonium phosphate and sodium hydroxide

31. Combustion Reactions
Chemical reaction that proceeds with the evolution of heat and usually a flame
General equation: hydrocarbon + oxygen carbon dioxide + water
Hydrocarbon: molecular compound that contains only carbon and hydrogen (gases)
Alcohol: molecular compound that contains carbon, hydrogen and ends in –OH (liquids)
Sugar: molecular compound that contains carbon, hydrogen, and oxygen (solids)

32. Combustion Reactions
Hydrocarbons: CxHy and the names of the compounds end in –ane, -ene, or –yne
Methane: CH4
Propane C3H8
Alcohols: CxHyOH and the names end in –ol
Ethanol: C2H5OH
Isopropyl alcohol: C3H7OH
Sugars: CxHyOz and names end in –ose
Glucose: C6H12O6
Sucrose: C12H22O11

33. Combustion Reactions
Identify the type of hydrocarbon present, predict the products, include physical states, and balance the equation:
C2H6
C6H5OH
C6H12O6